UMEM Educational Pearls - Toxicology

Category: Toxicology

Title: Scombroid

Keywords: scombroid, seafood (PubMed Search)

Posted: 5/27/2010 by Fermin Barrueto, MD (Updated: 5/28/2023)
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Scombroid is caused by ingestion of preformed histamine on skin of fish.

  • Naturally occurring histidine on scaly fish converted to histamine by surface bacteria - often fish left out too long, refrigeration will prevent the conversion.
  • Bacteria responsible are Morganelli morganii and K. pneumoniae
  • Fish: tuna, mahi mahi, amberjack, bonito, mackerel, albacore
  • Fish usually appears normal though meat may tast peppery
  • Patient presents minutes/hrs flushed, urticaria, HA, N/V
  • Self-limited and improve within hrs even without treatment
  • Antihistamines and rarley epinephrine will be needed

Category: Toxicology

Title: The "Other" Sodium Channel Blocking Agents

Keywords: sodium channel block, tricyclic antidepressant, cocaine, QRS (PubMed Search)

Posted: 5/13/2010 by Bryan Hayes, PharmD (Updated: 5/28/2023)
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We are all familiar with the classic ECG abnormalities caused by the sodium channel blocking properties of tricyclic antidepressants (QRS interval widening, R wave in aVR, S wave in I and aVL, and rightward deviation in terminal 40 msec of QRS). Here are some other medications that also block cardiac sodium channels in a similar manner:

  • Cocaine
  • Diphenhydramine
  • Cyclobenzaprine (Flexeril)
  • Carbamazepine (Tegretol)
  • Phenothiazines
  • Propoxyphene
  • Class 1A antidysrhythmics (quinidine, procainamide, disopyramide)
  • Class 1C antidysrhythmics (encainide, flecainide, propafenone, moricizine)
  • Amantadine

Category: Toxicology

Title: PRODUCT RECALL: Tylenol, Zyrtec and Motrin liquid

Keywords: Product recall, tylenol, zyrtec, motrin, pediatric, acetaminophen, ibuprofen, certirizine (PubMed Search)

Posted: 5/6/2010 by Ellen Lemkin, MD, PharmD (Updated: 5/28/2023)
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It is likely that you will be asked questions about the huge recall by McNeil..

It stems from complaints received of black particles found in the pediatric liquid formulation, which are manufactured at one facility in Fort Washington, PA.  The FDA inspected the plant and found inadequate quality standard testing and facilities. Either there were potential bacteria in one of the raw products (which did not make it to the final product), or the final concentrations were stronger than specified.

McNeil recalled forty-three formulations of pediatric liquid tylenol, zyrtec, motrin and benadryl. Generic versions are unaffected.

Complete recall information:

For more information and links:

Category: Toxicology

Title: Drug-Induced Thrombocytopenia

Keywords: heparin, cimetidine, thrombocytopenia (PubMed Search)

Posted: 4/22/2010 by Fermin Barrueto, MD (Updated: 5/28/2023)
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Here are is a list of common drugs that will cause thrombocytopenia as a result of antiplatelet antibodies (its not just heparin!). This list is not complete but are common ones that you will see in the ED, coming from USH or on the floors/units during residency:

Abciximab, Acetaminophen, amiodarone, amphotericin B, ASA

Carbamazepine, cimetidine



Quinidine, Quinine




Category: Toxicology

Title: Radiopaque Drugs on AxR

Keywords: iron, metals (PubMed Search)

Posted: 4/15/2010 by Fermin Barrueto, MD (Updated: 5/28/2023)
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Several drugs and compounds may be radiopaque on an abdominal radiograph. This may be helpful in an overdose to determine ingestion or amount ingested. Attached is a pic a patient that ingested potassium sustained release tables.

The mneumonic CHIPES will help you remember which are:

C - Calcium Carbonate, chloral hydrate

H - Heavy metal - like Mercury, lead

I - Iron and Iodine

P - Phenothiazines (compound that has S(C6H4)2NH in it), drugs that include: antipsychotics like chlorpromazine (thorazine) and antiemetics like prochlorperazine (compazine)

E - Enteric coated pills

S - Solvents [halogenated ones like chloroform] and Sustained Release preparations [Lithobid and K-Dur]


KCl_patient_1.JPG (182 Kb)

Category: Toxicology

Title: Toxin-Induced Nystagmus

Keywords: nystagmus, pcp, phenytoin (PubMed Search)

Posted: 4/8/2010 by Bryan Hayes, PharmD (Updated: 4/11/2010)
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Many drugs/toxins cause nystagmus, particularly in overdose.  Vertical, horizontal, or rotary nystagmus may be noted.

The most common drug/toxin overdoses that cause nystagmus are the following:

  • Anticonvulsants (phenytoin, carbamazepine, valproic acid, lamotrigine, topiramate)
  • Ethanol
  • Lithium
  • Dextromethorphan
  • Phencyclidine (PCP)
  • Ketamine
  • Lysergic acid diethylamide (LSD)

Category: Toxicology

Title: N-acetylcysteine

Keywords: acetaminophen; acetylcysteine (PubMed Search)

Posted: 4/2/2010 by Ellen Lemkin, MD, PharmD (Updated: 5/28/2023)
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Recently, a toxicoeconomic study was done to compare length of stay and costs of hospitalization of a group who received
IV n-acetylcysteine (n=191) to those received oral n-acetylcysteine (n=70) prior to the availability of the intravenous formulation.
What they found was that patients treated with IV acetylcysteine had a decreased length of stay (4 days vs 7 days, p< 0.001) and cost of hospitalization ($7,607 vs $18,287,  p<0.001) compared to the enteral group.

Show References

Category: Toxicology

Title: Tox Screen - The False Positives

Keywords: urine toxicology screen (PubMed Search)

Posted: 3/18/2010 by Fermin Barrueto, MD (Updated: 3/27/2010)
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When you draw a urine toxicology screen it can mislead more often than help you. Here is a quick list of the test followed by some medications that cause false positives - when in doubt, call your lab to find out specifics since results will vary lab to lab:

TCA - diphenhydramine, carbamazepine, cyclobenzaprine (side note: TCA screen should never be used to determine TCA toxicity, your ECG and physical exam should be enough to determine if the patient is toxic from TCA

Cocaine - the most accurate test on the screen, positive for up to 5 days

PCP - dextromethorphan and ketamine can turn it positive

Amphetamines - pseudoephedrine, ephedrine, phenylephrine and many other OTC cough decongestants can as well, the worst screening test with the largest number of false positives

Category: Toxicology

Title: Food allergy cross-reactivity

Keywords: food, allergy, propofol, soy, peanut, egg (PubMed Search)

Posted: 3/9/2010 by Bryan Hayes, PharmD (Emailed: 3/11/2010) (Updated: 3/20/2010)
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According to the Food Allergy and Anaphylaxis Network, the eight most common food allergies, which account for 90% of the food allergies in the U.S., are: dairy, soy, wheat, shellfish, fish, peanut, tree nut, and egg.

Several medications are formulated with these ingredients and should be avoided in patients with reported allergies.

  • Propofol is a lipid emulsion that contains egg.  Avoid in patient with hypersensitivity to eggs, egg products, soybeans, or soy products.
  • Ipratropium ± albuterol (Atrovent, Combvient®) inhalers may contain soy lecithin.  This can cause allergic reactions in patients with allergy to soy lecithin or related food products (e.g., soybean and peanut).  Nebulizer solutions (e.g., Duoneb®) seem to be free from this issue.
  • Progesterone (Prometrium®) capsules contain peanut oil.

Category: Toxicology

Title: Cutting Edge vs. Old School for Overdoses

Keywords: Lavage, activated charcoal, hyperinsulinemia, intralipid, toxicology, narcan (PubMed Search)

Posted: 3/4/2010 by Ellen Lemkin, MD, PharmD (Updated: 5/28/2023)
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Cutting Edge
Old School
  Gastric Lavage
Hyperinsulinemia and Euglycemia Supportive care, glucagon for beta blocker overdoses
Intralipid administration Supportive care for anesthetic overdoses, TCAs, and other lipid soluble agents
Low dose or NO narcan High dose narcan for opoid overdoses
Checking salicylates and tylenol levels for overdose Tox screens for everyone

Category: Toxicology

Title: Rodenticides

Keywords: cholecalciferol, brodifacoum (PubMed Search)

Posted: 2/18/2010 by Fermin Barrueto, MD (Updated: 5/28/2023)
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When a child is reported to be exposed to a rat poison it is commonly a long acting coumarin like brodifacoum. The rat usually eats the poison then during its traumatic little life will cause its own death by jumping and squeezing through a crack. When a human is exposed, this is the typical sequence of events:

  1. Exposure (and when you usually see them in the ED)
  2. 24-72 hrs later you will actually see an INR rise if actually ingested

Treatment is the same as for coumadin, vitamin K. However, do not start empirically since the patient will be committed to high doses of vitamin K for several months. Let the patient prove they have been poisoned which means they will require recheck of their INR 2-3 days later though they can be sent home with specific warning signs of anticoagulation.

Category: Toxicology

Title: Transplant Med Toxicology

Keywords: transplant, tacrolimus, sirolimus, cyclosporine (PubMed Search)

Posted: 2/9/2010 by Bryan Hayes, PharmD (Emailed: 2/11/2010) (Updated: 2/11/2010)
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With all of the post-transplant patients we see in the ED, a refresher on the toxicities associated with the most common immunosuppressant medications is warranted.


Cyclosporine (Sandimmune® and Neoral®/Gengraf®) and tacrolimus (Prograf®) are both calcineurin inhibitors that inhibit activation and proliferation of T-lymphocytes and IL-2.

-          Major concerns: Nephrotoxicity, drug interactions (CYP3A4)

-          Adverse Effects:

o       Electrolyte abnormalities: ­K+, ¯Mg+, ­glucose

o       CNS: HA, tremor (statistically higher with tacrolimus)

o       CV: HTN, ­ lipids (increased with cyclosporine)

o       End organ: hepatotoxicity, nephrotoxicity

o       Cosmetic (cyclosporine specific): hirsutism, gingival hyperplasia, acne


Sirolimus/Rapamycin (Rapamune®) is an M-tor inhibitor that inhibits T-lymphocyte activation and proliferation.

-          Major concerns: Drug interactions (CYP3A4)

-          Adverse Effects:

o       Delayed wound healing

o       Leucopenia, thrombocytopenia

o       Hypercholesterolemia

Category: Toxicology

Title: Broad spectrum antibiotics for multidrug resistant bacteria

Keywords: antibiotics, imipenem, meropenem, doripenem, ertapenem, colistin, amikacin, multiresistant (PubMed Search)

Posted: 2/4/2010 by Ellen Lemkin, MD, PharmD
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  • Broadest spectrum of activity of all classes
  • Imipenem has slightly better gm + activity; lowers seizure threshold
  • Meropenem has slightly better gm - activity
  • Ertapenem does not cover Pseudomonas
  • Doripenem has the most activity against Pseudomonas
  • May use in PCN allergic patients (cross reactivity lower than previously thought)


  • Has broad coverage, but does not cover Pseudomonas
  • Bacteriostatic; derivative of tetracycline
  • Does NOT require renal dosing
  • Higher mortality in VAP than other agents; do not use for intra-abdominal infections (poss higher risk of perforation)


  • Has antipseudomonal activity
  • Used in combination with other agents for MDR (multi-drug resistant) bacteria
  • Causes nephrotoxicity and ototoxicity


  • Bacteriocidal against many MDR gram - bacteria
  • Not active against Proteus, Provincia, Burkholderia, Neisseria, or Serratia
  • Nephrotoxicity and ototoxicity reported

Show References

Category: Toxicology

Title: RCIN Continued

Keywords: saline, sodium bicarbonate, acetylcystein (PubMed Search)

Posted: 1/28/2010 by Fermin Barrueto, MD (Updated: 5/28/2023)
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Apologies - last few bullets were cutoff - Continuing - Prophylaxis against RCIN has been attempted with the following:

  • IV saline infusion
  • Sodium Bicarbonate bolus
  • IV acetylcysteine infusion

No one therapy has been show to have superior efficacy.

Category: Toxicology

Title: Radiocontrast Induced Nephropathy

Keywords: RCIN, renal failure (PubMed Search)

Posted: 1/28/2010 by Fermin Barrueto, MD (Updated: 5/28/2023)
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Radiocontrast Induced Nephropathy (RCIN)

  • Occurs within 24 hrs of administration followed by oliguric phase
  • Usually improves within a week and rarely needs dialysis
  • Initial injection is an osmotic load, leads to volume expansion and diuresis. Follwed by intense vasoconstriction suggesting possible ischemic role in pathophysiology.
  • There is also a direct toxic effect to the kidneys however
  • High Risk patients: HTN, DM,  Chronic Renal Insuff, Bence Jones proteinuria and large injections of IV dye
  • Possible prophylaxis: There is almost no data studying this effect in the Emerg Dept patient. One trial look at IV acetylcysteine in the Emergent CT (RAPPID trial) did show benefit but has flaws within the study. IV hydration and sodium bicarbonate

Show References

Category: Toxicology

Title: Quinolone Induced Delirium

Keywords: levofloxacin (PubMed Search)

Posted: 1/21/2010 by Fermin Barrueto, MD (Updated: 5/28/2023)
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Quinolone Induced Deliurim

Just to give you another reason NOT to give a quinolone - aside from the C. diff. This adverse effect occurs with quinolones unlike many other antibiotics. It can prolong hospital stay, cause falls and further medical work ups. Some risk factors are:

  • Elderly
  • Renal Insufficiency
  • Benzodiazepine dependence (will actually precipitate withdrawal since quinolones displace the BDZ from the receptor - you have probably done this to a patient if you think about it, that may be why they went crazy)
  • Epilepsy - can cause seizures especially with NSAIDs


Category: Toxicology

Title: Anion Gap Metabolic Acidosis

Keywords: anion gap, metabolic acidosis (PubMed Search)

Posted: 1/14/2010 by Bryan Hayes, PharmD (Updated: 1/15/2010)
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As we are now into the winter months, exposures to ethylene glycol (antifreeze) and methanol (windshield washer fluid) increase.  Here is a good mnemonic for sorting through an anion gap metabolic acidosis:

C – cyanide, carbon monoxide
A – alcoholic ketoacidosis, acetaminophen (massive OD)
T – toluene (chronic from glue sniffing)
M – methanol, metformin
U – uremia
D – diabetic ketoacidosis
P – propofol infusion syndrome, propylene glycol, paraldehyde
I – iron, isoniazid, ibuprofen (massive OD)
L – lactic acidosis
E – ethylene glycol
S – salicylates, starvation ketoacidosis

Category: Toxicology


Keywords: DMSA, succimer, lead, arsenic, mercury (PubMed Search)

Posted: 1/7/2010 by Ellen Lemkin, MD, PharmD (Updated: 5/28/2023)
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  • An oral agent used for the chelation of heavy metals, such as LEAD, ARSENIC and MERCURY
  • Forms a water soluble agent that chelates the heavy metal, which are renally excreted
  • Most common side effects are rashes, urticaria and GI
  • A serious adverse effect is neutropenia, which is rare

Category: Toxicology

Title: Christmas Eve

Keywords: christmas rose (PubMed Search)

Posted: 12/24/2009 by Fermin Barrueto, MD (Updated: 5/28/2023)
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A quick christmas one:

The Christmas Rose (Helleborus niger)

Actually containes cardioactive steroids - eating it will help your A fib with RVR as it will act like digoxin, as well as kill like it.


christmasrose.jpg (30 Kb)

Category: Toxicology

Title: Drug Induced Parkinsonism

Keywords: manganese, parkinsons, tremor (PubMed Search)

Posted: 12/17/2009 by Fermin Barrueto, MD (Updated: 5/28/2023)
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Here is a table adapted from Goldfrank's Textbook of Toxicologic Emergencies 8th Edition - Drugs that May Induce Parkinsonism. MPTP is the story that everyone hears about and actually has links to Maryland. In 1976, Barry Kidston, a 23-year-old chemistry Maryland graduate student, synthesized MPPP (Meperidine or Demerol) incorrectly and injected the result. It was contaminated with MPTP, and within three days he began exhibiting symptoms of Parkinson's disease. Ooops - permanent.


  • Chemotherapeutics (several)
  • Cyclosporine
  • Calcium Channel Blockers
  • Dopaminergic withdrawal
  • Kava Kava (with manganese)
  • Progesterone
  • Sertraline
  • Valproic Acid
  • Trazodone


  • Carbon Monoxide
  • Cyanide
  • Heroin
  • Manganese
  • MPTP